It’s always in the shortest and coldest days of the year that Aloe aculeata spits out a flower spike. This makes them a bit vulnerable to frosty nights, since the soft and young, actively dividing cells of forming flower buds are not as resistant to cold as the tougher cells of mature leaves, so weather that doesn’t harm the leaves can terminate the new spike. I nursed this plant through about 23 degrees F a few nights ago (Dec 21, 2017) and hope that it will continue forth to put on its fiery display sometime in February. Don’t the tight bud scales look a bit like exotic koi goldfish at this stage of their development?

A view of the aloe with a few of its garden neighbors: Yucca linearifolia top left, Grusonia bradtiana middle, and Agave utahensis var eborispina top right.

One comment from a friend on Facebook where I also made this post said, “The fact that it blooms in winter seems like a pretty lame survival strategy.” To this, I replied, “It’s nowhere near as cold in South Africa where these are native to, so it’s not really a problem there. It’s my fault for taking them 11,000 miles away. They are genetically programmed by photoperiod sensitivity to initiate blooming during short days and cool nights, in preparation for a spring opening, which works out fine most years in their milder South African habitat than here in chillier Arizona.”

This led to a bit of discussion about whether a given plant can change and adapt to somewhat different conditions in a hemisphere with opposite seasons from what we deem “normal”. Basically, the answer is that in a case like this species, bloom timing appears to be hard-wired and not very flexible. It’s probably tied to day length, and to some extent cooler temperatures in combination with the short days. If it were temperature-dependent only, and cold were an inhibiting factor rather than an encouraging one, then these would not initiate flowering while the threat of freezing is present. (Which like I said, is lower in the winters of their native South Africa than in non-native Arizona.) Since none of my 5 or 6 garden Aloe aculeata plants have ever bloomed at any time other than this one (December – February, which would be equal to June – August in a South African winter) I believe that individual plants do not or cannot respond to extra cold to delay flower bud formation, and are stuck with whatever cycle their genetic blueprints dictate, as related to short-day photoperiods.

On a population-wide scale, however, there is always variance and there are probably plants that exist that are not as tied to this timing. If it were to prove fortuitous for those plants growing in a colder-than normal South African habitat to not set buds in frosty winter (June/July) weather, and delay it until it’s a bit warmer (maybe spring, Sept/October blooming instead) then over time natural selection would favor those spring bloomers instead, but mostly in those colder localities, and not necessarily everywhere else.

However individuals do not appear to evolve that way, since this dynamic is more of a long-term evolution process that acts upon the entire population across centuries or longer, as opposed to something mutable within the comparatively short lifespan of most individuals. That’s why despite facing cold every year in this unnatural northern hemisphere habitat, they still bloom at a “dangerous” time for them. If I were not to interfere and cover them against this freezing weather, all the aloes I have of this type would simply not reproduce (because of frost-killed flower buds) and the population would go extinct within a single generation. But if I were to grow 1000 or more of these, all from seed, and were to select only the ones that bloom later and let the others all die, and breed only the late bloomers, then I could eventually get a stand of Aloe aculeata that are adapted towards Arizona conditions that bloom in the safer weather of springtime, not winter. What works across larger populations and longer time scales might not apply to single individuals.

In other words, if I want to grow this species – and I do since it’s one of my few heat/cold/rabbit tolerant aloe options – then I have to live with their winter blooming and protect them from it. If I were to find plants for sale online from a spring blooming population (not even sure that exists, but theoretically) then that would be a better fit for me. But short of that, this is what I get.

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Addendum, Friday January 5, 2018: A few weeks after I made the post above, I took a really nice photo of the Aloe aculeata flower spikes at night. I featured this photo in a post made January 4, 2018 entitled “A Midwinter’s Night Dream” and discussed how I made the images I took. Click on the tag link “Aloe aculeata” at the bottom of this post and it should bring you to a menu that includes that post, if you want to read it. But briefly, since you are here, this photo was taken on a calm and mild moonlit night with a veil of mackerel sky cirrocumulus clouds. It is a 13 second time exposure using the significant lighting of a nearly full moon and a handheld LED headlamp to illuminate the foreground plants. Eventually in coming weeks I will likely add another photo or two of this flower spike actually open. Provided that the deer don’t find it and eat it first, which could definitely happen….

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Addendum 2: Following the successful seasonal progress of this particular plant and its flowering process, here is a photo I took on Friday February 9, 2018, a couple of months after the original post of the buds above. Obviously the deer respected the 8 foot barbed ire fencing I bothered to install last year (they don’t always and somehow squeeze through in weak spots) and the spike did not become fodder. It was worth the extra protective effort to enjoy this show, since I don’t always get to in between the weather and the critters.